Booster for amplifying the transmission output of a handy phone

ABSTRACT

A booster connectable to a handy phone for amplifying the transmission output of the phone is disclosed. A particular transmission message included in a transmission wave output from the phone and determining transmission power is decoded to generate a reference signal matching in level with the transmission power of the message. A variable gain power amplifier has its gain controlled such that the reference signal and the detected signal of the transmission wave output by the booster coincide with each other. As a result, the booster outputs power coincident with the transmission power determined by the particular transmission message. The booster makes it needless to inform the phone of the connection of the booster to the phone, and therefore obviates the need for extra connection lines and circuitry for detecting connection information. In addition, the booster is applicable to any kind of handy phone without regard to the manufacturer so long as a transmission wave includes a particular transmission message representative of transmission power.

BACKGROUND OF THE INVENTION

The present invention relates to a booster for a handy phone and moreparticularly to a booster for amplifying the transmission output of ahandy phone.

Handy phones in general are limited in battery capacity and heatradiation structure for implementing a light weight configuration andattractive appearance. Therefore, a transmission output available with ahandy phone is smaller than the transmission output of a fixedcommunication apparatus. To increase the transmission output of a handyphone, it is a common practice to connect an exclusive booster to thephone. However, should the booster be simply connected to the handyphone, it would obstruct ventilation and would thereby generateexcessive heat.

Japanese Patent Publication No. 3-20167, for example, discloses a deviceconstructed to reduce the heat generation of a handy phone. The deviceincludes a detecting circuit responsive to the connection of anexclusive booster to a handy phone. An automatic output power controlcircuit controls the transmission power of the phone to a preselectedvalue relating to a reference voltage. The output of the detectingcircuit is fed to a reference voltage generator included in theautomatic output power control circuit for generating the abovereference voltage, thereby varying the reference voltage. As a result,the output power of the phone is lowered to the minimum input necessaryfor the booster.

The device taught in the above document has some problems left unsolved,as follows. The device is not operable without the detecting circuitresponsive to the connection of the booster to the phone. The detectingcircuit needs extra connection lines because the connection of thebooster to the phone is usually implemented by physical connectionlines.

Assume that transmission power to be output from the booster changeswhen the booster is connected to the phone. Then, the class of atransmitter included in the phone and usually stored in the phone inrelation to its identification must be changed from one provided whenthe phone is used alone. In addition, such a condition must be reportedto a base station by using the replaced class. However, such informationis not necessary when it comes to a booster applicable to a cellularsystem because the output power of the booster does not have to bechanged from the original output power of the phone, i.e., the class ofa transmitter does not have to be changed.

Further, the above detecting circuit will probably differ from onemanufacturer to another manufacturer. It will therefore be difficult toconnect devices put on the market by different manufacturers.

Technologies relating to the present invention are also disclosed in,e.g., Japanese Patent Laid-Open Publication Nos. 4-361430, 7-336243,7-226710, and 8-195712.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a boosterfor a handy phone eliminating the need for extra connection lines.

It is another object of the present invention to provide a boosterconnectable to any kind of handy phone.

A booster for a handy phone of the present invention includes a variablegain power amplifier for amplifying the power of a transmission waveoutput from the phone to which the booster is connected. A splittingsection splits the transmission wave with the amplified power outputfrom the variable gain power amplifier into two. A decoder decodes aparticular transmission message included in the transmission wave splitby the splitting section and determining transmission power to therebyoutput a reference signal matching in level with the transmission power.A detector detects the transmission wave with the amplified power outputfrom the variable gain power amplifier. A controller compares the levelof the reference signal output from the decoder and the level of adetected signal output from the detector and variably controls the gainof the variable gain power amplifier such that the reference signal anddetected signal coincide with each other. A transmitting sectiontransmits the transmission wave output from the splitting section byradio.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription taken with the accompanying drawings in which:

FIG. 1 is a block diagram schematically showing a booster for a handyphone embodying the present invention; and

FIG. 2 is a schematic block diagram showing a specific configuration ofa decoder included in the illustrative embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring TO FIG. 1 of the drawings, a booster for a handy phoneembodying the present invention is shown. As shown, the booster includesa first duplexer 12 and a second duplexer 21 connected to a phoneconnection terminal 11 and an antenna 22, respectively. The firstduplexer 12 is connected to a variable gain power amplifier 13 and avariable gain, low noise amplifier 20. A coupler 14 is connected toground at one end of its secondary side via a resistor 15. A signaloutput from the coupler 14 is input to a decoder 16. A diode 17 and acapacitor 118 constitute a detector for detecting the output signal ofthe decoder 16. A controller 19 controls the entire booster.

A transmission wave output from a handy phone, not shown, is input tothe booster connected to the handy phone via the phone connectionterminal 11. The first duplexer 12 routes the transmission wave to thetransmitting side, i.e., delivers it to the variable gain poweramplifier 13. The power amplifier 13 amplifies the transmission wavewith a gain controlled by the controller 19. The amplified transmissionwave output from the power amplifier 13 is split into two by the coupler14. One of the split waves is input to the second duplexer 21 while theother wave is input to the decoder 16. The decoder 16 decodes a messageincluded in the input wave. At the same time, the detector made up ofthe diode 17 and capacitor 18 detects the envelope of the input wave.

The controller 19 receives the output of the decoder 16 and the outputof the detector. In response, the controller 19 controls the gain of thevariable gain power amplifier 13 and that of the variable gain, lownoise amplifier 20 such that the detected signal level coincides withthe result of decoding. The wave fed from the amplifier 13 to the secondduplexer 21 is radiated via the antenna 22.

On the other hand, a wave sent from a remote station and come in throughthe antenna 22 is fed to the variable gain, low noise amplifier 20 viathe second duplexer 21. The amplifier 20 amplifies the received wavewith a gain controlled by the controller 19. The amplified wave outputfrom the amplifier 20 is delivered to the handy phone via the firstduplexer 12 and phone connection terminal 11.

FIG. 2 shows a specific configuration of the decoder 16. As shown, thetwo split transmission waves are respectively applied to mixers 161 and162 via an input terminal 160. A signal output from a PLL (Phase LockedLoop) 166 is applied to the mixer 161 and is applied to the mixer 162via a phase shifter 163. The phase shifter 163 shifts the phase of theoutput of the PLL 166 by 90°. The mixers 161 and 162 execute quadraturedemodulation with the input transmission waves by using the output ofthe PLL 166 and the output of the phase shifter 163, respectively. Theresulting baseband signals output from the mixers 161 and 162 are inputto a frequency offset estimation 164. The frequency offset estimation164 outputs a frequency offset value based on the two baseband signals.

The above frequency offset value is fed back to a voltage controlled,temperature compensation type quartz oscillator (VCTCXO) 165 and theninput to the PLL 166. The output oscillation frequency of the PLL 166 istherefore corrected by the frequency offset value. The output of thefrequency offset estimation 164 is applied to a data separation 16 aswell. The data separation 167 separates the transmission power of thephone or a parameter included in an algorithm for determining thetransmission power and inputs the parameter to a calculation andconversion 168. The calculation and conversion 168 calculates, based onthe input parameter, power to be actually transmitted from the phone andgenerates a reference voltage matching in level with the calculatedpower. The reference voltage is fed from the decoder 16 to thecontroller 19 via an output terminal 169.

A specific operation of the illustrative embodiment will be describedwith reference to FIGS. 1 and 2. In some handy phone systems, a handyphone or mobile station operated to send a wave to a base station sendsits transmission power or a parameter used to calculate the transmissionpower to the base station either constantly or periodically. The basestation uses such information to monitor the handy phone. For example,assume that the transmission level of the handy phone is high, but thelevel reaching the base station is low. Then, the base stationdetermines that the distance between it and the handy phone hasincreased, and commands the phone to further raise the transmissionlevel.

Usually, the above transmission power information has a preselectedformat. That is, information showing where and how (coding method) thetransmission power information is written in transmission data isparticular to the system and known beforehand. Therefore, the decoder 16shown in FIGS. 1 and 2 is so constructed as to decode the abovetransmission power information. As shown in FIG. 2, the decoder 16 issimilar in construction to a receiving section included in aconventional digital cellular mobile station. Although the PLL 166 mustshare the same frequency as the handy phone and must therefore searchfor a desired frequency by itself, this kind of technology is notdirectly relevant to the present invention and will not be describedspecifically.

The transmission wave is input to the mixers 161 and 162 via the inputterminal 160, as stated with reference to FIG. 2. The mixers 161 and 162execute quadrature demodulation with the input waves by using the outputof the PLL 166 and the output of the phase sifter 163. The resultingbaseband signals output from the mixers 161 and 162 are input to thefrequency offset estimation 164. At this instant, the frequency offsetestimation 164, for example, must be provided with an analog-to-digitalconversion capability at its input side in order to implement digitalsignal processing to follow.

In the illustrative embodiment, the frequency offset estimation 164determines a difference between a reference signal output from themodulation circuit of the handy phone and a reference signal output fromthe demodulation circuit of the booster by use of a conventional method.The different is fed back from the estimation 164 to the VCTCXO 165. Asa result, the output oscillation frequency of the VCTCXO 165 is causedto coincide with the reference signal frequency of the handy phone andthen input to the PLL 166. The PLL 166 multiplies the frequency of theinput signal. The resulting output of the PLL 166 is directly fed to themixer 161 as a carrier for demodulation and is fed to the mixer 162after being shifted in phase by 90° by the phase shifter 163.

At the same time, the frequency offset estimation 164 delivers signalsoutput from the mixers 161 and 162 and undergone quadrature demodulationto the data separation 167. The data separation 167 separates thetransmission power information mentioned earlier and feeds it to thecalculation and conversion 168. The calculation and conversion 168calculates, based on the transmission power information, power to beactually transmitted from the handy phone, generates a reference voltagematching in level with the calculated power, and delivers the referencevoltage to the controller 19, FIG. 1, via the output terminal 169.

The controller 19 compares the reference voltage and the detectedvoltage output from the detector made up of the diode 17 and capacitor18. The detected voltage varies in accordance with the gain of thevariable gain power amplifier 13. Therefore, the controller 19 outputs acontrol voltage for controlling the gain of the amplifier 13 such thatthe above detected voltage coincides with the reference voltage outputfrom the decoder 16. The controller 19 may be implemented byconventional circuitry including, e.g., an operational amplifier.

The transmission wave amplified by the power amplifier 13 is radiatedfrom the booster via the coupler 14, second duplexer 21, and antenna 22.At this instant, it is noteworthy that due to the control over the gainof the power amplifier 13, the power of the wave radiated via theantenna 22 has a value represented by the transmission power informationincluded in the transmission wave.

Further, the controller 19 can see, based on the control voltage meantfor the variable gain power amplifier 13, the gain of the amplifier 13.The controller 19 therefore sets a gain identical with the gain of thepower amplifier 13 in the variable gain, low noise amplifier 20. As aresult, the low-noise amplifier 20 amplifies a signal received via theantenna 22 and second duplexer 21 with the same gain as the poweramplifier 13. The amplified received signal is routed through the firstduplexer 12 and phone connection terminal 11 to the handy phoneconnected to the terminal 11. This successfully corrects the insertionloss of the above booster and handy phone connected together withrespect to both of transmission and receipt.

As stated above, in the illustrative embodiment, the decoder 16 decodesa particular message determining the transmission power of the handyphone and included in a transmission wave output from the phone, therebyoutputting a reference voltage. The booster causes the reference voltageand the detected voltage of the transmission wave output from thevariable gain power amplifier 13 to coincide with each other. As aresult, the transmission wave amplified by the power amplifier 13 issent with transmission power determined by the above particular message.This makes it needless for information showing the connection of thebooster to the phone to be input to the phone, and thereby eliminatesthe need for a circuit for detecting the connection of the booster andextra connection lines. Because connection lines are absent, theillustrative embodiment is applicable to any kind of handy phone.

In summary, it will be seen that the present invention provides abooster for a handy phone making it needless to inform the phone of theconnection of the booster to the phone, and therefore obviating the needfor connection lines and circuitry for detecting connection information.In addition, the booster of the present invention is applicable to anykind of handy phone without regard to the manufacturer so long as atransmission wave to be sent includes a particular messagerepresentative of transmission power.

Various modifications will become possible for those skilled in the artafter receiving the teachings of the present disclosure withoutdeparting from the scope thereof. For example, the frequency offsetestimation 164 may be omitted if the modulation system is not sensitiveto frequency variation, i.e., if the oscillation frequency of the VCTCXO165 can be confined in an allowable frequency deviation range.

What is claimed is:
 1. A booster for a handy phone, comprising: avariable gain power amplifier for amplifying power of a transmissionwave output from the handy phone to which said booster is connected;splitting means for splitting the transmission wave with amplified poweroutput from said variable gain power amplifier into two; a decoder fordecoding a particular transmission message included in the transmissionwave split by said splitting means and determining transmission power tothereby output a reference signal matching in level with saidtransmission power, said decoder comprising a demodulating section forexecuting quadrature demodulation with the transmission wave output fromsaid splitting means, a calculating and converting section forcalculating transmission power of said particular transmission messageoutput from a data separating section, and generating said referencesignal matching in level with calculated transmission power, a frequencyoffset estimating section for determining, based on a demodulated signaloutput from said demodulating means, a difference in frequency betweenthe handy phone and said reference signal, and correcting means forcorrecting, in response to an output signal of said frequency offsetestimating section, a frequency of a carrier meant for said demodulatingmeans; a detector for detecting the transmission wave with amplifiedpower output from said variable gain power amplifier; a controller forcomparing a level of said reference signal output from said decoder anda level of a detected signal output from said detector and variablycontrolling a gain of said variable gain power amplifier such that saidreference signal and said detected signal coincide with each other; anda transmitting means for transmitting the transmission wave output fromsaid splitting means by radio.
 2. A booster as claimed in claim 1,further comprising a variable gain, low noise amplifier for receipt,said controller variably controlling a gain of said variable gain lownoise amplifier in accordance with the gain of said variable gain poweramplifier.
 3. A booster as claimed in claim 2, further comprising: afirst duplexer for selectively connecting an input terminal of saidvariable gain power amplifier and an input terminal of said variablegain, low lose amplifier to a phone connection terminal connected to thehandy phone; and a second duplexer for selectively connecting an outputterminal of said variable gain power amplifier and an output terminal ofsaid variable gain, low noise amplifier to a transmit/receive antenna.4. A booster as claimed in claim 1, wherein said detector detects anenvelope of transmission wave split by said splitting means and theninput to said decoder.